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bike carb to throttle body conversion on a zetec
Fishface - 6/4/14 at 04:13 PM

Is it easy to convert to throttle bodies? I dont want to change my fuel tank or fit another fuel line, can I use a swirl pot thingy?????

Thanks

big_wasa - 6/4/14 at 04:20 PM

You still need a return but that could be added to the fuel sender.

Fishface - 6/4/14 at 04:26 PM

ah thanks, thats what worried me. I really dont fancy running another line and the hassle with the tank but I suppose the benefits will outweight the effort. Is it east to fit to a sender?

big_wasa - 6/4/14 at 04:49 PM

There are many ways to do it. You can buy a barb that just bolts into the top of the tank. They are sold as aircraft fittings.

Fishface - 6/4/14 at 05:08 PM

interesting, sounds like i need to do plenty of research.
Maybe i will stick with bike carbs

whitestu - 6/4/14 at 05:33 PM

I've seen plenty of Zetec cars on TBs and they don't seem to run any better or go any faster than mine on bike carbs on a stock engine.

I quite fancy the idea of EFI and TBs but I have the feeling it won't work as well without a lot of fiddling.

Stu

DavidW - 6/4/14 at 09:08 PM

quote:
Originally posted by whitestu
I've seen plenty of Zetec cars on TBs and they don't seem to run any better or go any faster than mine on bike carbs on a stock engine.

I quite fancy the idea of EFI and TBs but I have the feeling it won't work as well without a lot of fiddling.

Stu


Having pondered this 'upgrade' this is interesting. I'd like to know if anyone has made similar observations?

David

Paul Turner - 7/4/14 at 11:26 AM

My 2 litre appeared to run fine on 45's despite the horror stories about progression. It was way better than the previous x-flow. mpg was in the mid 20's which was better than the x-flow. Both engines had 3D ignition and the same carbs.

But on fuel injection the car is better, the pick up is instant and the mpg is in the low 30's.

But I was lucky, used a guy who knew his Webers, problem is that today they are few and far between. Get a muppet and it will run like a dog. There are far more tuners out there who can sort injection TB's.

But the only alternative to adding a fuel return and a swirl pot with LP and HP pumps is to fit a special injection tank with baffles and a submerged pump, but it still needs a fuel return.

My return is also by the gauge sender, bolted in a simple union.

[Edited on 7/4/14 by Paul Turner]

coozer - 7/4/14 at 12:00 PM

Ok chaps my St170 made 166 on the rollers with ZX9R carbs. However they were straight off a1.8 with NO rejetting before the session..

Then I decided to go EFI.. after buying a MS, struggling with that and then an Omex 600 which worked straight out the box and a mapping session on the rollers it made 178.. that cost me somewhere near £2K..

In hindsight I would stick with the carbs and get them set up correctly. I would rather have spent the money on cams and head work and kept the carbs...

IMO DONT DO IT!

RichardK - 7/4/14 at 02:03 PM

I agree with Coozer, if you've got a set of decent sized carbs and they are setup correctly the improvement in swapping to TB's is negligible versus cost, however if starting from scratch I'd probably go TB if I was to do it all over again now but if skint then it's carbs all the way

Cheers

R

DavidW - 7/4/14 at 02:03 PM

Coozer - I'm still running your 1.8 zetec and it's doing well.

David

daveb666 - 7/4/14 at 02:09 PM

I've always had TBs before so wanted them again with this car. The ability to 'fault-find' and retain a turn-key start regardless of the weather appeals to me so that's the route I went.

I've never had carbs, but the whole technology behind carbs just seems old to me and TBs are a 'modern-day' carb. I also retain the ability to tweak and map myself if needed.

As seen in my project thread

GXR1000 Bodies - £75 (ebay)
ST170 Manifold and Fuel Rail - £40 (ebay)
MBE Loom & ECU - £250 (ebay)
Mapping - £500 (Noble motorsport)

All in the best part of £900 but I could have had it mapped cheaper but took it to the same place I always did that I have a lot of trust in.

whitestu - 7/4/14 at 02:56 PM

quote:

I've always had TBs before so wanted them again with this car. The ability to 'fault-find' and retain a turn-key start regardless of the weather appeals to me so that's the route I went.

I've never had carbs, but the whole technology behind carbs just seems old to me and TBs are a 'modern-day' carb. I also retain the ability to tweak and map myself if needed.


That's what attracts me as well, but my bike carbs seem to do everything you have listed except ability to easily adjust the map.

So far I've been able to do all the adjusting I need via jet sizes and needle position though without the need for an RR session.


Stu

mcerd1 - 7/4/14 at 03:44 PM

quote:
Originally posted by Paul Turner
My 2 litre appeared to run fine on 45's despite the horror stories about progression. It was way better than the previous x-flow. mpg was in the mid 20's which was better than the x-flow. Both engines had 3D ignition and the same carbs.

But on fuel injection the car is better, the pick up is instant and the mpg is in the low 30's.

from what I've been told you can get much better MPG figures from bike carbs than you can from twin 45's
(variable-venturi and no accelerator pumps etc..)

Scuzzle - 7/4/14 at 04:09 PM

From what I can tell throttle bodies seem to give 10 BHP more than bike carbs when both are all set up properly. I've seen a few cars go from bike carbs to throttle bodies and when they hit the rollers it's always 10 BHP of a difference.

coozer - 7/4/14 at 05:12 PM

quote:
Originally posted by DavidW
Coozer - I'm still running your 1.8 zetec and it's doing well.

David


Excellent, still getting 40mpg?

Steve